As an image forming apparatus, there is known a printer including a process cartridge detachably provided thereto. The process cartridge includes a drum cartridge which supports a photosensitive drum and a developing cartridge which supports a developing roller and is detachably provided to the drum cartridge.
As the developing cartridge provided to the printer, there is suggested a developing cartridge including a lower frame which supports a developing roller, and an upper frame connected to the lower frame by welding (for example, refer to JP-A-2009-168993).
In the developing cartridge, the upper frame has a main body part having a plate shape and a beam part that is provided at a front end of the main body part, and a periphery of a lower surface of the main body part is formed with welding ribs that are welded on upper surfaces of a left-side wall part, a right-side wall part and a back-side wall part of the lower frame.
When the upper frame and the lower frame are connected, a front end of the beam part of the upper frame and front faces of the left-side wall part and right-side wall part of the lower frame configure a substantially same plane. A seal member is provided between the beam part of the upper frame and the left-side and right-side wall parts of the lower frame.
In the developing cartridge described in JP-A-2009-168993, the main body part of the upper frame and the left-side, right-side and back-side wall parts of the lower frame are welded. However, the beam part of the upper frame and the left-side and right-side wall parts of the lower frame are not welded each other.
Therefore, in order to seal a space between the beam part of the upper frame and the left-side and right-side wall parts of the lower frame, the seal member is inevitably provided, so that it is difficult to reduce the number of parts.